Image display method, image display device, and image display program

ABSTRACT

An image reproduction function for reproducing effectively reproducing image recorded in a storage device in diversified forms is provided. A moving picture obtained from one image pickup device is recorded in a plurality of systems at different frame rates. The recorded moving picture is formed of a plurality of still picture data. When reproducing the recorded moving picture, the still picture data forming a moving picture of either one of the systems are reproduced according to a time axis serving as reference for reproduction of the recorded moving picture.

INCORPORATION BY REFERENCE

The present application claims priority of Japanese Patent ApplicationNo. 2004-022106 filed on Jan. 29, 2004, and the content of which isincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an image reproduction method. Inparticular, the present invention relates to an image reproductionmethod for effectively reproducing image data recorded, for example, indiversified forms.

BACKGROUND ART

With the spread of network communication, a system in which a user in aremote place can display a picture (such as a moving picture, a stillpicture, or an intermittent quasi-moving picture having consecutivestill pictures in a time series manner) picked up by a camera on ascreen by using a client device such as a personal computer or a mobiletool is put into operation.

Such a system is utilized in various uses. For example, such a system isutilized as a surveillance system for monitoring an intruder or anabnormality in a management subject (see, for example,JP-A-2003-274383).

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

As for delivery of image data to a client device, typically image datapicked up by a camera is stored in a server and the image data isdelivered from the server to the client device. However, it is expectedthat the recording form of image data stored in the server isdiversified in the future to improve the convenience of the user as thesystem described above spreads. For example, even if image data is videodata obtained from the same camera, qualities (such as the resolution,compression factor and frame rate (fps: frame per second)) are changedin some cases according to the time zone, occurrence of a specificabnormality or the like by considering the communication load of thenetwork, the storage capacity of the server, or the like.

However, the conventional system is not sufficient for effectivelyreproducing image data recorded in diversified forms.

In view of the foregoing situations, the present invention has beenachieved. An object of the present invention is to provide an imagereproduction method for effectively reproducing image data recorded, forexample, in diversified forms.

MEANS FOR SOLVING THE PROBLEM

In an image reproduction method according to the present invention, amoving picture obtained from one image pickup device is recorded in aplurality of channel lines by using a plurality of different frame ratesand the recorded moving picture is reproduced. The recorded movingpicture includes a plurality of still picture data. The still picturedata that forms a moving picture of one channel line in the channellines is reproduced in accordance with a time axis that serves as areference for reproducing the recorded moving picture.

Here, “record in a plurality of channel lines” refers to record a videoimage obtained from one image pickup device into a plurality of channelsin one recording device or in different recording devices underdifferent video conditions, or record a video image obtained from oneimage pickup device in a situation similar to them.

Here, “video condition” refers to, for example, the resolution and thecompression factor, besides the frame rate.

In the description in the present specification, the term “image” isused. For example, however, the term “video image” is also a similarterm, and it is incorporated in the present invention.

In the description in the present specification, the term “reproduction”is used. For example, however, the term “display” or “perusal” is also asimilar term, and it is incorporated in the present invention.

In the description in the present specification, the term “recording” or“storage” is used. For example, however, the term “record” or “imagerecording” is also a similar term, and it is incorporated in the presentinvention.

If the still picture data that form moving pictures of at least twochannel lines among channel lines are image data generated at the sametime, then the still picture data that forms a moving picture of achannel line having a high frame rate is reproduced, according to theimage reproduction method of the present invention.

Here, it may be determined considering, for example, time correspondingto an error caused when providing image data with time information,whether times of the generated image data are “the same time.”

While the still picture data that forms a moving picture of a channelline having a high frame rate is consecutively present, the stillpicture data that forms the moving picture of the channel line havingthe high frame rate is reproduced, according to the image reproductionmethod of the present invention.

In an image reproduction method according to the present invention, amoving picture obtained from one image pickup device is recorded in aplurality of channel lines by using at least one of different framerates, different compression factors, and different resolutions and therecorded moving picture is reproduced. The recorded moving pictureincludes a plurality of still picture data. The still picture data thatforms a moving picture of one channel line in the channel lines isreproduced in accordance with a time axis that serves as a reference forreproducing the recorded moving picture.

If the still picture data that form moving pictures of at least twochannel lines among channel lines are image data generated at the sametime, then the still picture data that forms a moving picture of achannel line having a high frame rate, a low compression factor, or ahigh resolution is reproduced, according to the image reproductionmethod of the present invention.

While the still picture data that forms a moving picture of a channelline having a high frame rate, a low compression factor, or a highresolution is consecutively present, the still picture data that formsthe moving picture of the channel line having the high frame rate, thelow compression factor, or the high resolution is reproduced, accordingto the image reproduction method of the present invention.

ADVANTAGES OF THE INVENTION

According to the image reproduction method of the present invention,image data recorded, for example, in diversified forms can beeffectively reproduced as heretofore described.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment according to the present invention will be described withreference to drawings.

Hereafter, an embodiment of the present invention will be described withreference to the drawings.

FIG. 1 shows an embodiment of a general configuration of an imagestorage and delivery system to which the image reproduction methodaccording to the present invention is applied.

The image storage and delivery system in the present embodiment includesan image storage and delivery server 1 provided with a random-accessiblerecording device (hereafter referred to as disk device) 3 for storingimage (including voice in some cases) data, a plurality of web cameras(5-1 to 5-n) connected to the image storage and delivery server 1 via anetwork 4, and a plurality of client terminals 6 (6-1 to 6-m).

In the image storage and delivery system according to the presentembodiment, image data from one web camera 5 is divided into a pluralityof channels (in the present embodiment, two channels) and recordedaccording to the recording mode. Therefore, each of the web cameras 5-1to 5-n has a plurality of unique channel numbers. For example, the webcamera 5-1 is a web camera for channel 1 (ch1) and channel 2 (ch2), . .. , and the web camera 5-n is a web camera for channel p-1 (chp-1) andchannel p (chp). Here, each of n, m and p is a natural number. It is notalways necessary to satisfy the relation n=m=p, but the combination ofthem can be selected arbitrarily.

Image data of each frame in video images picked up by the web cameras5-1 to 5-n is compressed according to an image compression techniquesuch as JPEG and transmitted to the image storage and delivery server 1in an IP packet form. In this case, the compressed image data becomesvariable length data which differs in data quantity from frame to frame.The image storage and delivery server 1 extracts compressed image data(hereafter referred to simply as image data) from packets received fromthe web cameras 5-1 to 5-n via the network, and stores the image data instorage areas 30 (30-1 to 30-p) previously secured in the disk device 3so as to be associated with the channels, respectively.

As a result, an image of one web camera 5 is stored in each storage area30 in a time series manner. At the time of recording, a frame number isassigned to each image data every frame for the purpose of control. Inthe image storage and delivery system, it is also possible to use adevice having a function obtained by integrating the function of theimage storage and delivery server 1, the function of the disk device 3and so on.

Each client terminal 6 requests the image storage and delivery server 1to deliver image data by specifying a channel number and a frame number.In response to a request from the client terminal, the image storage anddelivery server 1 serves to deliver image data having the specifiedchannel number/frame number read out from the disk device 3 to theclient terminal 6 of the request origin in an IP packet form. As aresult, each client terminal 6 can reproduce image data recorded in thedisk device 3.

The image reproduction method according to the present invention isapplied in the case that the client terminal 6 requests the imagestorage and delivery server 1 to deliver image data and reproduces theimage data on a monitor of the client terminal 6.

As recording modes mounted on the image storage and delivery system,there are three kinds, i.e., scheduled picture recording, manual picturerecording and alarm picture recording according to difference in triggercause.

In the scheduled picture recording, image data from the web camera 5 isrecorded in accordance with a time table preset by a user. In the manualpicture recording, the user who is monitoring an image on the monitor ofthe client terminal 6 records image data supplied from a web camera 5 atarbitrary timing by conducting GUI operation (such as pressing of apicture recording button) on the client terminal 6. In the alarm picturerecording, image data supplied from the web camera 5 is recorded inresponse to an alarm signal input to the web camera 5 (such as contactinput from an external sensor or intruder sensing conducted by imagerecognition processing).

Recording modes other than these three recording modes may be used. Inthe ensuing description, the schedule picture recording and the manualpicture recording are referred to as normal picture recording, and astorage area 30 in the disk device 3 into which recording is conductedby the normal picture recording is referred to as normal channel (normalch). A storage area 30 in the disk device 3 into which recording isconducted by the alarm picture recording is referred to as alarm channel(alarm ch).

FIG. 2 is a diagram showing recording contents of a disk deviceaccording to an embodiment of the present invention.

As shown in FIG. 2, the following mode is used because of physicalrestrictions of the recording capacity of the disk device 3. That is, inconducting the normal picture recording, image data is recorded into thenormal channel at a low frame rate. In conducting the alarm picturerecording, image data is recorded into the alarm channel at a high framerate only when an alarm has occurred. As for the alarm picturerecording, an image over a predetermined time period before alarmoccurrence time (a pre-alarm image) is recorded by going back in timeseries from the alarm occurrence as indicated by “alarm channel” in FIG.2.

Here, the case where the normal picture recording differs from the alarmpicture recording only in the frame rate of recorded image data will bedescribed as an example. In addition, however, it is possible toarbitrarily set recording contents in respective recording modes, suchas a change in the compression factor or resolution of the image,according to the setting situation of the actual system. As anotherembodiment, it is possible to record image data at a higher frame rate,a lower compression factor or a higher resolution in the alarm picturerecording than the normal picture recording.

FIG. 3 is a diagram showing operation of recording into a disk deviceaccording to an embodiment of the present invention.

A configuration of the web camera 5 and the image storage and deliveryserver 1 used when recording image data supplied from the web camera 5in the storage areas 30-1 (ch1) and 30-2 (ch2) in the disk device 3 byusing the normal picture recording or the alarm picture recording willnow be described with reference to FIG. 3. For brevity, theconfiguration will now be described by taking the web camera 5-1included in the web cameras 5 as an example.

The web camera 5-1 includes an image pickup unit 50, an encoder 51, atransmission video memory 52, a transmission video memory 52 (ringbuffer) 53, and a network interface (I/F) 54.

The image storage and delivery server 1 includes a network interface(I/F) 10, a received video memories 11 (11-1 to 11-2), and a diskinterface (I/F) 12. The web camera 5-1 and the image storage anddelivery server 1 are connected to each other via the network I/Fs 54and 10. The image storage and delivery server 1 and the disk device 3are connected to each other via the disk I/F 12.

The image pickup unit 50 in the web camera 5-1 picks up an image of apredetermined visual field range. A video signal obtained by the imagepickup is input to the encoder 51 at a frame rate of, for example, 30fps, i.e., at time intervals of 30 frames per second. The encoder 51conducts compression encoding on the video signal by using, for example,the JPEG form, and generates image data.

The image data encoded by the encoder 51 is input to the transmissionvideo memory 52 at, for example, 30 fps, and stored in the transmissionvideo memory 52 temporarily. If image data of one new frame is inputfrom the encoder 51 to the transmission video memory 52, then thetransmission video memory 52 discards image data stored until then andstores the new image data. When conducting the normal picture recording,a CPU (not illustrated) in the image storage and delivery server 1transmits an image data delivery request to the web camera 5-1 inaccordance with a normal picture recording rate (frame rate) preset in adata memory (not illustrated) in the image storage and delivery server1.

Upon receiving the image data delivery request, the web camera 5-1transmits image data of one frame stored in the transmission videomemory 52 at that time point to the image storage and delivery server 1.In the case of the normal picture recording, the image storage anddelivery server 1 sends the image data delivery request to the webcamera 5-1 repetitively from picture recording start until picturerecording end set by a user of, for example, client terminal 6-1. Theimage storage and delivery server 1 temporarily stores the receivedimage data in the received video memory 11-1, and then records the imagedata in the storage area 30-1 (ch1) in the disk device 3 used as thenormal channel of the web camera 5-1, via the disk I/F 12.

In the method adopted in the present embodiment, image data is deliveredvia the network 4 frame by frame whenever a request is issued. Asanother embodiment, a method of delivering image data corresponding to aplurality of frames (or image data corresponding to one file) inresponse to each request may also be adopted.

Furthermore, in the present embodiment, the image data output from theweb camera 5 is intermittent and it is a moving picture that isconsecutive in time series. However, a different form may be used.

In the system configuration of the pull type as in the presentembodiment, the web camera 5 delivers image data in response to access(a delivery request) from the image storage and delivery server. Asanother embodiment, a system configuration of push type may also beused. In the system configuration of push type, the web camera 5delivers image data at, for example, predetermined timing without accessfrom the server 1.

The image data encoded by the encoder 51 is input to the transmissionvideo memory 53 at an alarm picture recording rate (frame rate) presetfor a data memory (not illustrated) in the web camera 5-1, and stored inthe transmission video memory 53 temporarily. Unlike the transmissionvideo memory 52, the transmission video memory 53 has a configurationcapable of retaining image data corresponding to a plurality of framessuch as 100 frames. This is because in the alarm picture recording it isnecessary to record image data (pre-alarm image) over a predeterminedtime period before the alarm occurrence as described above.

If an external sensor (not illustrated) connected to the web camera 5-1is activated and an alarm signal is input to the web camera 5-1, then analarm occurrence notice is transmitted from the web camera 5-1 to theimage storage and delivery server 1. Upon receiving the alarm occurrencenotice, the CPU in the image storage and delivery server 1 starts alarmpicture recording. When conducting the alarm picture recording, the CPUin the image storage and delivery server 1 specifies time that precedesalarm occurrence time by a predetermined time period and transmits animage data delivery request to the web camera 5-1. The web camera 5-1transmits image data stored in the transmission video memory 53beginning with the specified time to the image storage and deliveryserver 1.

The image storage and delivery server 1 temporarily stores receivedimage data in the received video memory 11-2, and then stores the imagedata in the storage area 30-2 (ch2) in the disk device 3 used as thealarm channel for the web camera 5-1, via the disk I/F 12.

Transmission of image data from the web camera 5-1 to the image storageand delivery server 1 is continued until end of the alarm which hasoccurred. In other words, if the operation of the external sensor stopsand an alarm end notice is transmitted from the web camera 5-1 to theimage storage and delivery server 1, then the CPU in the image storageand delivery server 1 which has received the alarm end notice stops theimage data delivery request.

Image data stored in the transmission video memory 53 is image data readout from the encoder 51 and stored in the transmission video memory 53in accordance with the alarm picture recording rate by the CPU (notillustrated) in the web camera 5-1. In the case of the alarm picturerecording, therefore, the CPU in the image storage and delivery server 1does not perform a control concerning the frame rate when sending animage data delivery request to the web camera 5-1, but requests the webcamera 5-1 to deliver all image data in the transmission video memory 53for the time zone from the alarm occurrence to the alarm end (includingthe pre-alarm image), unlike the case of the normal picture recording.

As described above, the image data delivery request is stopped bytransmission of the alarm end notice to the image storage and deliveryserver 1. Besides this mode, another mode may also be used as adifferent embodiment. For example, the image data delivery request isstopped a predetermined time period after the time when the imagestorage and delivery server 1 received the alarm occurrence notice(post-alarm picture recording).

For example, time information of the frame (hereafter referred to astime stamp), a frame number which indicates the order of image pickup ineach channel, and frame rate information (the normal picture recordingrate or the frame picture recording rate) are attached to the image datarecorded in the storage area 30 in the disk device 3 as additionalinformation.

The time stamp is generated by using the time when the image data isgenerated by the encoder 51 in the web camera 5 and the time when theimage storage and delivery server 1 receives the image data from the webcamera 5. For example, when generating the time stamp by using the timewhen the image storage and delivery server 1 receives the image datafrom the web camera 5, the time stamp may be calculated according to thetechnique described hereafter.

As an example, in the case of the normal picture recording, the timewhen image data is received is used as the time stamp of the image data.On the other hand, in the case of the alarm picture recording, there isa predetermined time period over which image data is retained in thetransmission video memory 53. In such a case, for example, a differencebetween the time when the web camera 5 delivers the image data from thenetwork I/F 54 and the time when the encoder 51 generates the image datais found, and the found difference is subtracted from the time when theimage storage and delivery server 1 receives the image data. In the caseof the alarm picture recording, therefore, a value obtained by thesubtraction is used as the time stamp of the image data.

In the present embodiment, the normal picture recording rate is set bythe image storage and delivery server 1, whereas the alarm picturerecording rate is set by the web camera 5. However, it is possible toarbitrarily select setting destinations of these kinds of informationaccording to the configuration of the actual system.

For example, if a memory for temporarily retaining image datacorresponding to a plurality of frames, such as the transmission videomemory 53 shown in FIG. 3, is not provided in the web camera 5, butprovided in the image storage and delivery server 1, then the alarmpicture recording rate may be set by the image recognition server 1.

The image reproduction method according to the present invention willnow be described.

As the image reproduction method used when reproducing the image data ofa predetermined web camera 5 recorded in the disk device 3, on themonitor of the client terminal 6, there are three image reproductionmethods: “reproducing only the normal channel,” “reproducing only thealarm channel,” and “conducting seamless reproduction (which will bedescribed in detail later).” For example, a GUI operation view forselecting one of these image reproduction methods is displayed on adisplay screen of the monitor of the client terminal 6. The user canselect one of the image reproduction methods by depressing a button onan input device such as a mouse. Hereafter, these three imagereproduction methods will be described in detail.

FIG. 4 is a diagram showing operation of “reproducing only the normalchannel.” In FIG. 4, the horizontal direction represents the timedirection, and a picture recording time period in each channel isrepresented by a rectangle. A part represented by a thick line arrow inFIG. 4 is reproduced. The same is true of FIGS. 5 and 6 described lateras well. When “reproducing only the normal channel,” only image datarecorded in a predetermined normal channel, such as the storage area30-1 in the disk device 3 (the normal channel of the web camera 5-1), isread out in the order of time series and reproduced on the monitor ofthe client terminal 6, as shown in FIG. 4.

FIG. 5 is a diagram showing operation of “reproducing only the alarmchannel.” When “reproducing only the alarm channel,” only image datarecorded in a predetermined alarm channel (such as the storage area 30-2in the disk device 3 (the alarm channel of the web camera 5-1)) is readout in the order of time series and reproduced on the monitor of theclient terminal 6, as shown in FIG. 5.

As represented by a dotted line arrow in FIG. 5, reproduction is skippedover a time period having no image data. Video reproduction is continuedover a time period having the next image data. In a configuration inwhich each image data is provided with a frame number indicating theorder of image pickup when image data generated by the web camera 5 isrecorded in the storage area 30 in the disk device 3, the clientterminal 6 requests the image storage and delivery server 1 to deliverimage data in the order of frame number. As a result, it is possible toimplement the image reproduction method shown in FIG. 4 and FIG. 5.

FIG. 6 is a diagram showing operation of “seamless reproduction”according to an embodiment of the present invention. The “seamlessreproduction” is an image reproduction method executed by the followingalgorithm as shown in FIG. 6. If image data is present in the alarmchannel at certain time when reproducing the video image along the timeseries, then the image data in the alarm channel is reproducedregardless of whether image data is present in the normal channel. Ifimage data is not present in the alarm channel but image data is presentonly in the normal channel, then the image data in the normal channel isreproduced. If image data is present in neither of the channels, it isalso possible to skip until time when image data is present in eitherchannel and continue reproduction of the image data.

The reason why reproduction of the image data in the alarm channel isprovided with priority is as follows: as for a section in which imagedata is present in both the alarm channel and the normal channel asshown in FIG. 6, it is possible to ascertain contents in more detail byreproducing the image data in the alarm channel having the image datarecorded at high frame rate.

In the system of the present embodiment, the frame rate and the imageresolution and compression factor at the time when conducting the alarmpicture recording and the normal picture recording can be arbitrarilyset. When image data is present in both channels at the same time,therefore, it is possible to arbitrarily set a channel to be givenpriority in reproduction of image data according to the settingsituation of the actual system. By the way, a decision whether imagedata is present in each channel at each time may be made by comparingreproduction reference time generated at the start time of reproductionof image data with the time stamp provided for image data taken out fromeach channel. Here, the reproduction reference time means, for example,a time axis serving as the reproduction reference.

FIG. 7 is a flow chart showing basic operation of image reproductionprocessing (seamless reproduction) 700 according to an embodiment of thepresent invention.

An example of a flow of image reproduction processing executed by theclient terminal 6 will now be described with reference to FIG. 7.

In the image reproduction processing 700, the current system time(current time) is first stored in a data memory (not illustrated)included in the client terminal 1 as control time (step 701).

A time stamp of image data currently displayed on the monitor of theclient terminal 6 is stored in the data memory as the reproductionreference time (step 702). The processing at the step 702 is processingfor setting the reproduction start time of image data. Instead of themode in which the time stamp of the image data currently displayed onthe monitor of the client terminal 6 is used as the reproduction starttime as described above, various modes may also be used as a differentembodiment. For example, the user of the client terminal 6 is caused tospecify the reproduction start time.

It is determined whether the client terminal 6 is currently acquiringimage data of the alarm channel or the normal channel in the disk device3 via the image storage and delivery server 1 (step 703). At step 709described later, the client terminal 6 requests the image storage anddelivery server 1 to deliver predetermined image data. Until the clientterminal 6 finishes acquiring the image data, however, the processingdoes not branch to next step 704 (the decision at the step 703 is yes).If the client terminal 6 is not currently acquiring image data, theprocessing branches to the next step 704 (the decision at the step 703is no).

Subsequently, the client terminal 6 calculates a difference betweencontrol time stored in the data memory and the current system time, andstores the calculated time in the data memory as “delay time” (step704). After the client terminal 6 has found the delay time, it storesthe current system time in the data memory as new control time, andupdates the control time. Therefore, the delay time is time between theend of the processing at the step 704 in FIG. 7 and the re-start of theprocessing at the step 704.

Subsequently, the client terminal 6 adds the delay time calculated atthe step 704 to the reproduction reference time stored in the datamemory, and updates the reproduction reference time (step 705). Theclient terminal 6 can set the reproduction timing of image data in theclient terminal 6 to the actual time elapse by conducting the processingat the step 705 of updating the reproduction reference time by means ofthe delay time and processing at step 708 described later.

Subsequently, the client terminal 6 acquires a frame number and a timestamp of the latest acquired image from a reproduced image memory foralarm channel and a reproduced image memory for normal channel (step706).

The reproduced image memory will now be described. FIG. 8 is a diagramshowing one configuration example of a reproduced image memory includedin the client terminal 6. The reproduced image memory includes areproduced image memory 81 for normal channel and a reproduced imagememory 82 for alarm channel. Each of the memories 81 and 82 has an areafor temporarily retaining image data corresponding to at least twoframes, i.e., corresponding to one frame in a last acquired imagestorage area and one frame in a latest acquired image storage area. Whenconducting image reproduction processing shown in FIG. 7, the clientterminal 6, which has received image data recorded in the alarm channelin the disk device 3 via the image storage and delivery server 1, storesthe image data in the latest acquired image storage area in thereproduced image memory 82 for alarm channel. The same is true of thenormal channel as well.

By the way, the client terminal 6 stores image data acquired last timein the last acquired image storage area in order to update thereproduced image memory at step 709 described later.

Subsequently, a time stamp of the latest acquired image in thereproduced image memory 82 for alarm channel and a time stamp of thelatest acquired image in the reproduced image memory 81 for normalchannel acquired at the step 706 are compared with the reproductionreference time (step 707). If at least one of the time stamps of thelatest acquired images for alarm channel and for normal channelindicates time before the reproduction reference time (time earlier thanthe reproduction reference time), the processing branches to the step708. On the other hand, if the time stamps of both the latest acquiredimages indicate time after the reproduction reference time (time laterthan the reproduction reference time), then the processing branches tostep 711.

If the decision at the step 707 is yes, then the client terminal 6calculates a frame number of image data to be acquired subsequently asto a channel in which the latest acquired image is judged to have a timestamp preceding the reproduction reference time at the step 707 (step708). If the time stamp of the latest acquired image in both the alarmchannel and the normal channel is judged to precede the reproductionreference time, then the client terminal 6 calculates a frame number ofimage data to be acquired subsequently in both channels.

Here, calculation of the frame number is conducted by using, forexample, the delay time obtained at the step 704.

If the delay time is short in a configuration in which image datarecorded in respective channels of the disk device 3 are provided withframe numbers in the order of time series, then image data to beacquired subsequently is image data in the next frame of the latestacquired image data currently retained by the client terminal 6 (inother words, a frame number of image data to be acquired subsequently isset equal to a number obtained by adding 1 to the frame number acquiredat the step 706). On the other hand, if the delay time is long, thenimage data to be acquired subsequently is image data of three framesafter the latest acquired image data currently retained by the clientterminal 6 (in other words, a frame number of image data to be acquiredsubsequently is set equal to a number obtained by adding 3 to the framenumber acquired at the step 706).

Specifically, if, for example, image data recorded in certain channel ofthe disk device 3 is 30 fps, then the frame number is increased by 1 atintervals of 33 msec. If the delay time obtained at the step 704 is 100msec, then the delay time (100 msec) is divided by the frame interval(33 msec) and the quotient value 3 is added to the frame number of thelatest acquired image data retained by the client terminal 6. This framenumber is used as a frame number of image data for which the clientterminal 6 sends a delivery request to the image storage and deliveryserver 1. As described above, as for frame rate information (having aframe interval of 33 msec in the above-described example) forcalculating the frame number, for example, frame rate informationretained by the latest acquired image data in the reproduced imagememory as additional information can be used.

Subsequently, the client terminal 6 requests the image storage anddelivery server 1 to deliver image data having the frame numbercalculated at the step 708 (step 709).

If the latest acquired image data judged to precede the reproductionreference time at the step 707 belongs to the alarm channel, then theclient terminal 6 requests the image storage and delivery server 1 todeliver-image data of the alarm channel at the step 709. If the latestacquired image data judged to precede the reproduction reference timebelongs to the normal channel, then the client terminal 6 requests theimage storage and delivery server 1 to deliver image data of the alarmchannel at the step 709.

If the latest acquired image data judged to precede the reproductionreference time belongs to both the alarm channel and the normal channel,then the client terminal 6 requests both the alarm channel and thenormal channel to deliver image data having the frame number calculatedat the step 708, at the step 709. When requesting the image storage anddelivery server 1 to deliver new image data, the client terminal 6updates the reproduced image memory with respect to the channel forwhich the delivery request is conducted. For example, when the clientterminal 6 issues a delivery request of new image data of the alarmchannel at the step 709, image data stored in the latest acquired imagestorage area in the reproduced image memory 82 for alarm channel beforethat time is stored in the last acquired image storage area. And theimage data for which the client terminal 6 has newly issued a deliveryrequest at the step 709 is received from the image storage and deliveryserver 1, and then stored in the latest acquired image storage area inthe reproduced image memory 82 for alarm channel.

Subsequently, the client terminal 6 selects image data to be reproducedon the monitor from the reproduced image memories 81 and 82, and outputsthe image data to the monitor (step 710).

Details of the step 710 will be described later with reference to FIG.9. In the present embodiment, the reproduced image selection processingat the step 710 is described as processing (step) in the flow chartshown in FIG. 7. Alternatively, the reproduced image selectionprocessing may be executed independently with due regard to timerequired to draw the image data on the monitor.

If the time stamps of the latest acquired images in both channels of theclient terminal 6 are judged to be after the reproduction reference timeat the step 707, then the client terminal 6 does not issue a deliveryrequest for new image data (the processing at the step 708), but storesa time stamp that indicates earlier time (time relatively in the past)in the latest acquired images in the reproduced image memories 81 and 82respectively for alarm channel and normal channel, into the data memoryas skip decision time (step 711).

Subsequently, the client terminal 6 makes a decision whether adifference between the skip decision time set at the step 711 and thereproduction reference time is at least 3 seconds (step 712). If thedifference is at least 3 seconds, then the processing branches to step713. If the difference is not at least 3 seconds, then processing at thestep 713 is not conducted, but the processing branches to step 714.

If the decision at the step 712 is yes, then the client terminal 6stores the skip decision time in the data memory as new reproductionreference time (step 713).

The 3 seconds is an example of a reference value for determining whetherto skip the reproduction reference time by a predetermined time period,on the basis of a difference between the reproduction reference time anda time stamp of image data to be reproduced subsequently. The referencevalue may be set arbitrarily according to the setting situation of theactual system. For example, the client terminal 6 can skip a time zoneduring which image data is not present in the channel of the disk device3, and reproduce image data, by setting this reference value equal to asuitable value. After the client terminal 6 has updated the reproductionreference time by using the skip decision time, the client terminal 6may store the current system time in the data memory as new control timeand update the control time.

Subsequently, the client terminal 6 makes a decision whether an imagedata reproduction stop order has been issued from the user of the clientterminal 6. If a reproduction stop order is issued, then the imagereproduction processing is terminated. If a reproduction stop order isnot issued, then the processing branches to the step 703 (step 714).

An example of processing conducted at the step 710 shown in FIG. 7 willnow be described in detail with reference to FIG. 9.

In the reproduced image selection processing (step 710), the clientterminal 6 first compares the time stamp of the last acquired image inthe reproduced image memory 81 for normal channel with the time stamp ofthe last acquired image in the reproduced image memory 82 for alarmchannel (step 901).

If the time stamp of the last acquired image in the reproduced imagememory 82 for alarm channel is judged to be later as a result of thecomparison, then the processing branches to step 902. If the time stampof the last acquired image in the reproduced image memory 82 for alarmchannel is judged to indicate the same time as the time stamp of thelast acquired image in the reproduced image memory 81 for normal channeldoes, then the processing branches to the step 902 in the same way. Onthe other hand, if the time stamp of the last acquired image in thereproduced image memory 81 for normal channel is judged to be later as aresult of the comparison, then the processing branches to step 903.

If the decision at the step 901 is yes, then the client terminal 6 readsout the last acquired image from the reproduced image memory 82 foralarm channel, outputs the last acquired image to the monitor, andreproduces the image data (step 902). In the present embodiment, thetime stamp of the image data stored in the last acquired image storageareas in the reproduced image memories 81 and 82 becomes time earlier(in the past) than the reproduction reference time, when conducting theprocessing at the step 710. Therefore, image data having a later timestamp included in the last acquired images for alarm channel and normalchannel is image data at time closer to the reproduction reference time.

The reason why the processing branches to the step 902 even if the timestamp of the last acquired image in the reproduced image memory 82 foralarm channel is judged to indicate the same time as the time stamp ofthe last acquired image in the reproduced image memory 81 for normalchannel does is that the image data in the alarm channel is to bereproduced when image data at the same time are present in the alarmchannel and the normal channel, as mentioned above with FIG. 6.

If the decision at the step 901 is yes, then the client terminal 6calculates a difference in time stamp between the latest acquired imageand the last acquired image in the reproduced image memory 82 for alarmchannel (step 903).

Subsequently, the client terminal 6 reads out frame rate informationgiven to the last acquired image in the reproduced image memory 82 foralarm channel as additional information, and calculates an alarmcontinuation decision value (step 904). For example, if the frame rateinformation added to the last acquired image in the reproduced imagememory 82 for alarm channel is 15 fps, then the frame interval iscalculated as 66 msec. The client terminal 6 sets a value of 86 msecobtained by adding a margin value of, for example, 20 msec to 66 msec asthe alarm continuation decision value.

Subsequently, the client terminal 6 compares the difference calculatedat the step 903 with the alarm continuation decision value calculated atthe step 904 (step 905). If the difference is found as a result of thecomparison to be equal to or less than the continuation decision value,then the processing branches to the step 902. Because it can bedetermined whether the image data currently retained in the lastacquired image storage area in the reproduced image memory 82 for alarmchannel of the client terminal 6 is image data in a time period overwhich image data is consecutively recorded in the alarm channel of thedisk device 3 at a predetermined frame rate, by comparing the alarmcontinuation decision value calculated on the basis of the frame rateinformation with the difference calculated at the step 903.

In other words, the client terminal 6 determines whether the retainedimage data is image data in a time period in which one alarm picturerecording operation started by an alarm caused at certain time iscontinued, or image data at a boundary point between one alarm picturerecording operation started by an alarm caused at certain time andanother alarm picture recording operation started by an alarm caused atdifferent later time. As a result, while one alarm picture recordingoperation is being continued, reproduction of image data in the normalchannel is not conducted on the way, but reproduction of the image datain the alarm channel is given priority.

Even if, for example, the last acquired image in the normal channel isjudged at the step 901 to be image data at time closer to thereproduction reference time than the last acquired image in the alarmchannel, therefore, the processing branches to the step 902 and the lastacquired image in the alarm channel is reproduced as long as one alarmpicture recording operation is continued.

A concrete example of the processing shown in FIG. 9 will be describedlater with reference to FIG. 10A and FIGS. 11A to 11D. On the otherhand, as a result of the comparison at the step 905, if the differencein time stamp is greater than the alarm continuation decision value, theprocessing branches to step 906.

If the decision at the step 905 is yes, then the client terminal 6 readsout the last acquired image from the reproduced image memory 81 fornormal channel, outputs the last acquired image to the monitor, andreproduces the image data (step 906).

A concrete example of image reproduction processing described withreference to FIGS. 7 and 9 will now be described with reference to FIGS.10A, 10B, 10C and FIGS. 11A to 11D.

FIG. 10A is a diagram showing an example of recording contents in thenormal channel and the alarm channel of the disk device 3. Withreference to FIG. 10A, image data of one web camera 5 is recorded in thenormal channel at 4 fps, and image data of the web camera 5 is recordedin the alarm channel at 18 fps. As for the alarm channel, the case wherealarm picture recording operation is conducted twice in total, once forframe numbers 1 to 7 and once for frame numbers 8 to 12 is shown.

In FIG. 10A, time indicated by a position of a left side of a squarefigure which indicates each image data is a time stamp that the imagedata has. Values such as 4 fps and 18 fps are value used for convenienceof description. As described above, the normal picture recording rateand the alarm picture recording rate can be set arbitrarily according tothe setting situation of the actual system. For example, if a camera foracquiring image data at 30 fps (at intervals of 33 msec) is used, it issuitable to set 30 fps, 15 fps, 10 fps, 6 fps, 5 fps, 3 fps, 2 fps, 1fps or the like which becomes a multiple of 33 msec as the normalpicture recording rate or the alarm picture recording rate.

In the case that the disk device 3 has recording contents as shown inFIG. 10A in the normal channel and the alarm channel, and that theclient terminal 6 conducts the image reproduction processing shown inFIGS. 7 and 9, FIGS. 11 to 11D show recording contents in the reproducedimage memory 81 for normal channel and the reproduced image memory 82for alarm channel, and image data reproduced from them.

FIG. 11A shows the case where the reproduction reference time is locatedon t1. FIG. 11B shows the case where the reproduction reference time islocated on t2. FIG. 11C shows the case where the reproduction referencetime is located on t3. FIG. 11D shows the case where the reproductionreference time is located on t4. By the way, FIGS. 11A to 11D showstates obtained immediately after the reproduced image selectionprocessing at the step 710 in FIG. 7 has been conducted.

First, the case where the reproduction reference time is located on t1will now be described. At the step 707 in FIG. 7, the time stamps of thelatest acquired images (both having the frame number 2 in FIG. 10A) inthe alarm channel and the normal channel at that time point coincidewith the reproduction reference time t1. Therefore, the processingbranches to the step 708. At the step 708, a frame number 3 iscalculated as image data to be acquired subsequently, in both the alarmchannel and the normal channel.

Subsequently, at the step 709, the client terminal 6 requests the imagestorage and delivery server 1 to deliver image data having the framenumber 3 in the alarm channel and the normal channel. Subsequently, theclient terminal 6 updates the reproduced image memories 81 and 82, andstores image data having the frame number 2 in the last acquired imagestorage areas, as shown in FIG. 11A. Image data having the frame number3 which are requested to be delivered at the step 709 and which arecurrently being acquired via the image storage and delivery server 1 arestored in the latest acquired image storage areas.

Subsequently, in the reproduced image selection processing at the step710, the time stamps of the last acquired images (both having the framenumber 2 in FIG. 10A) in the alarm channel and the normal channel atthat time point coincide with each other. Therefore, the decision at thestep 901 in FIG. 9 is yes.

At the step 902, the last acquired image (having the frame number 2 inFIG. 10A) in the alarm channel is selected and output to the monitor.

The case where the reproduction reference time is located on t2 will nowbe described.

At the step 707 in FIG. 7, the time stamp of the latest acquired image(having the frame number 3 in FIG. 10A) in the alarm channel at thattime point coincides with the reproduction reference time t2. Therefore,the processing branches to the step 708. At the step 708, a frame number4 is calculated as image data to be acquired subsequently in the alarmchannel.

Subsequently, at the step 709, the client terminal 6 requests the imagestorage and delivery server 1 to deliver image data having the framenumber 4 in the alarm channel. The client terminal 6 updates thereproduced image memory 82, and stores image data having the framenumber 3 in the last acquired image storage area, as shown in FIG. 11B.Image data having the frame number 4 which is requested to be deliveredat the step 709 and which is currently being acquired via the imagestorage and delivery server 1 is stored in the latest acquired imagestorage area.

Subsequently, in the reproduced image selection processing at the step710, the time stamp of the last acquired image (having the frame number3 in FIG. 10A) in the alarm channel at that time point is later than thetime stamp of the last acquired image (having the frame number 2 in FIG.10A) in the normal channel. Therefore, the decision at the step 901 inFIG. 9 is yes.

At the step 902, the last acquired image (having the frame number 3 inFIG. 10A) in the alarm channel is selected and output to the monitor.

The case where the reproduction reference time is located on t3 will nowbe described.

At the step 707 in FIG. 7, the time stamp of the latest acquired image(having the frame number 3 in FIG. 10A) in the normal channel at thattime point coincides with the reproduction reference time t3. Therefore,the processing branches to the step 708. At the step 708, a frame number4 is calculated as image data to be acquired subsequently in the normalchannel.

Subsequently, at the step 709, the client terminal 6 requests the imagestorage and delivery server 1 to deliver image data having the framenumber 4 in the normal channel. The client terminal 6 updates thereproduced image memory 81, and stores image data having the framenumber 3 in the last acquired image storage area, as shown in FIG. 11C.Image data having the frame number 4 which is requested to be deliveredat the step 709 and which is currently being acquired via the imagestorage and delivery server 1 is stored in the latest acquired imagestorage area.

Subsequently, in the reproduced image selection processing at the step710, the time stamp of the last acquired image (having the frame number3 in FIG. 10A) in the normal channel at that time point is later thanthe time stamp of the last acquired image (having the frame number 6 inFIG. 10A) in the alarm channel. Therefore, the decision at the step 901in FIG. 9 is no, and the processing branches to the step 903. At thetime point t3, one alarm picture recording being constituted of theframe numbers 1 to 7 is continuing. At the step 905 subsequent to thesteps 903 and 904, therefore, the difference in time stamp between thelatest acquired image and the last acquired image in the alarm channelbecomes smaller than the alarm continuation decision value. At the step905, therefore, the decision is no.

At the step 902, the last acquired image (having the frame number 6 inFIG. 10A) in the alarm channel is selected and output to the monitor.

The case where the reproduction reference time is located on t4 will nowbe described.

At the step 707 in FIG. 7, the time stamp of the latest acquired image(having the frame number 4 in FIG. 10A) in the normal channel at thattime point coincides with the reproduction reference time t4. Therefore,the processing branches to the step 708. At the step 708, a frame number5 is calculated as image data to be acquired subsequently in the normalchannel.

Subsequently, at the step 709, the client terminal 6 requests the imagestorage and delivery server 1 to deliver image data having the framenumber 5 in the normal channel. The client terminal 6 updates thereproduced image memory 81, and stores image data having the framenumber 4 in the last acquired image storage area, as shown in FIG. 11D.Image data having the frame number 5 which is requested to be deliveredat the step 709 and which is currently being acquired via the imagestorage and delivery server 1 is stored in the latest acquired imagestorage area.

Subsequently, in the reproduced image selection processing at the step710, the time stamp of the last acquired image (having the frame number4 in FIG. 10A) in the normal channel at that time point is later thanthe time stamp of the last acquired image (having the frame number 7 inFIG. 10A) in the alarm channel. Therefore, the decision at the step 901in FIG. 9 is no, and the processing branches to the step 903.

At the time point t4, one alarm picture recording operation for theframe numbers 1 to 7 is already finished. At the step 905 subsequent tothe steps 903 and 904, therefore, the difference in time stamp betweenthe latest acquired image and the last acquired image in the alarmchannel becomes greater than the alarm continuation decision value. Atthe step 905, therefore, the decision is yes. At the step 906, the lastacquired image (having the frame number 4 in FIG. 10A) in the normalchannel is selected and output to the monitor.

In the case that the disk device 3 has recording contents as shown inFIG. 10A in the normal channel and the alarm channel and that the clientterminal 6 conducts the image reproduction processing shown in FIGS. 7and 9, FIG. 10B shows reproduction of resultant image data.

If image data is present in both the normal channel and the alarmchannel at the same time as shown in FIG. 10B, then reproduction of theimage data in the alarm channel is given priority. For example, sinceimage data having the frame number 2 in the normal channel and the alarmchannel have the same time stamp, reproduction of the image data havingthe frame number 2 in the alarm channel is conducted, whereasreproduction of the image data having the frame number 2 in the normalchannel is not conducted. Furthermore, while alarm picture recording iscontinuing (i.e., while image data in the alarm channel are presentconsecutively at a predetermined frame rate), reproduction of image dataof the frame numbers 3 and 6 in the normal channel is not conducted.

In the case that the disk device 3 has recording contents as shown inFIG. 10A in the normal channel and the alarm channel and that the clientterminal 6 conducts other image reproduction processing obtained bymodifying a part of the image reproduction processing shown in FIGS. 7and 9, FIG. 10C shows resultant reproduced image data.

In FIG. 10C, the processing of the steps 903 to 905 shown in FIG. 9 isnot conducted. If the decision at the step 901 is no, then theprocessing branches to the step 906. In other words, the processing ofgiving priority to the reproduction of the image data in the alarmchannel during consecutive alarm picture recording is not conducted.Regardless of whether the channel is the alarm channel or the normalchannel, therefore, reproduction of the image data is conducted in theorder of time series. As shown in FIG. 10C, therefore, reproduction ofthe image data of the frame numbers 3 and 6 in the normal channel isalso conducted. By the way, in FIG. 10C as well, image data having theframe number 2 in the normal channel which has the same time stamp asthe image data having the frame number 2 in the alarm channel does isnot reproduced.

When conducting alarm picture recording in the disk device 3, a tablefor managing contents of alarm picture recording as shown in FIG. 14 isgenerated for each web camera 5 as another implementation means of theimage reproduction method according to the present invention. Whenconducting seamless reproduction, the client terminal 6 may refer to thetable stored in the image storage and delivery server 1.

By referring to such a table, it is possible to previously grasp a timezone (between alarm picture recording start time and alarm picturerecording end time) over which image data is recorded in the alarmchannel of the disk device 3 and frame numbers (alarm picture recordingstart frame number to alarm picture recording end frame number) of imagedata in that time zone. By using an algorithm for reproducing image datarecorded by normal picture recording in a time zone where image dataobtained by alarm picture recording is not present, seamlessreproduction in the client terminal 6 can be implemented.

If such an algorithm is used, as shown in the step 901 in the FIG. 9, itbecomes unnecessary to conduct processing of comparing the time stamp inthe alarm channel with the time stamp in the normal channel wheneverreproducing image data corresponding to one frame.

The embodiment has been described by taking the case where image data isreproduced in the forward direction as an example. Although there is aprocessing difference as to whether the delay time is added to orsubtracted from the reproduction reference time, it is also possible toimplement the seamless reproduction by conducting similar processing inreproduction of the backward direction (from later time toward earliertime) as well.

If multiplied speed playback such as half speed playback, double speedplayback or quadruple speed playback is conducted in forwardreproduction, a configuration in which a result obtained by multiplyingthe delay time calculated at the step 704 and a multiplied speedcoefficient (for example, 2 in the double speed playback) is added tothe reproduction reference time to update the reproduction referencetime at the step 705 in FIG. 7 may be used.

Furthermore, the case where a deviation quantity occurs between the timestamp of the image data in the normal channel and that in the alarmchannel as shown in FIG. 10A has been described as an example. (Forexample, image data of the frame number 3 in the normal channel andimage data of the frame number 6 in the alarm channel). As anotherembodiment, it is also possible to use a configuration in whichoccurrence of the deviation quantity is prevented by setting the normalpicture recording rate and the alarm picture recording rate equal to apredetermined frame rate.

In the above-described embodiment, a mode of reproducing high frame rateimage data by reproducing image data in the alarm channel preferentiallyis adopted. As another embodiment, however, it is also possible to use amode of reproducing, for example, image data of low compression factoror image data of high resolution preferentially in the case where imagedata differing in frame rate, compression factor or resolution arerecorded in the alarm channel and the normal channel.

In the above-described embodiment, a mode of forming the alarm channeland the normal channel on different storage areas of one disk device isused. As another embodiment, however, it is also possible to use a modeof forming the alarm channel and the normal channel in different diskdevices.

Hereafter, the background of the technique concerning the presentinvention will be described. All items described here are notnecessarily conventional techniques.

In the above-described example, the configuration for recording imagedata by using different channels, i.e., the normal channel and the alarmchannel when conducting the normal picture recording and the alarmpicture recording with respect to one web camera 5 is used. Hereafter, aconfiguration for recording image data in one channel when conductingthe normal picture recording and the alarm picture recording will bedescribed with reference to FIGS. 12 and 13.

FIG. 12 is a diagram showing an example of processing conducted whenrecording image data in one channel in the normal picture recording andalarm picture recording.

As shown in FIG. 12, the image storage and delivery server 1 records thevideo image of the web camera at a specified frame rate in a time periodbetween time t0 and t2. If occurrence of an alarm is detected on thebasis of an alarm signal input from an external sensor at the time t2,then the image storage and delivery server 1 acquires a video image ofthe web camera 5 from time t1 preceding the time t2 by a definite timeperiod, and starts video recording.

The reason why the video image is recorded from the time t1 is to recordthe pre-alarm image as well. This video image has been buffered in analarm video buffer (corresponding to, for example, the transmissionvideo memory 53 shown in FIG. 3) of the web camera. The image storageand delivery server 1 overwrites the video image on the video imagebetween t1 and t2 already recorded, and conducts time differencerecording of a video image between t2 and t3 (which is referred to astime difference recording because a time series is traced back and avideo image preceding the alarm occurrence time (i.e., the pre-alarmimage) is also recorded unlike the normal picture recording).

By the way, it is supposed that continuation of the alarm signal inputfrom the external sensor is completed and end of the alarm is detected,at time t3. Therefore, alarm picture recording of the video image of theweb camera 5 ranging from time t1 to t3 finishes at time t4=t3+(t2−t1).In other words, the image storage and delivery server 1 records thevideo image ranging from t1 to t3 as alarm picture recording over a timeperiod between t2 and t4. And the image storage and delivery server 1resumes the video recording using the normal picture recording after thetime t4.

Conducting the processing shown in FIG. 12 poses a problem that anunrecorded section (recording loss) is caused between t3 and t4. FIG. 13is a diagram showing an example of processing for solving the recordingloss shown in FIG. 12. In the processing shown in FIG. 13, a video imageranging from time t1 to t3 is recorded over a time period between t2 andt3. In other words, the recording interval is made shorter than usual toexecute picture recording at high rate. However, the high rate picturerecording has, for example, a problem (1) a time period over which onealarm picture recording operation continues cannot be predictedbeforehand and a suitable shortening quantity of the recording intervalcannot be calculated, because it cannot be known when an alarm which hasoccurred will finish. Such a problem can be avoided by determining aminimum value of an alarm picture recording continuation time period.However, this results in constraints on system construction.Furthermore, there is, for example, a problem (2) the processing loadimposed on the image storage and delivery server 1 becomes greater thanthe normal time over the high rate picture recording. In other words, itbecomes necessary to weave a load increase for high rate picturerecording into the picture recording performance of the image storageand delivery server 1 as a margin. In addition, there is a possibilitythat alarm occurrences will come in from a plurality of web cameras 5asynchronously, i.e., a possibility that a large number of alarms willoccur at the same time. Therefore, it is necessary to add margins ofload increases for respective alarms to calculate the performancespecifications of the image storage and delivery server 1. This isinadvisable in performance specifications. As for picture recording inthe time difference picture recording section, therefore, it is betterto conduct picture recording at normal recording intervals whilemaintaining the time difference (FIG. 12) than the high rate picturerecording (FIG. 13). There is also a method of always continuing thenormal picture recording and the alarm picture recording in one channelwhile maintaining the time difference. However, a loss in the videoimage caused by sudden interruption of power supply is conceivable. Acountermeasure such as installation of an UPS (Uninterruptible PowerSupply) becomes necessary. A problem of, for example, a higher systemcost also occurs.

On the other hand, in the configuration according to the embodiment ofthe present invention, the normal picture recording and the alarmpicture recording are conducted using separate channels. For example,therefore, the problem described with reference to FIGS. 12 and 13 canbe solved. By the way, a video image in the same time zone isredundantly recorded in, for example, two channels, i.e., the normalchannel and the alarm channel. As compared with the configurations shownin FIGS. 12 and 13, therefore, an extra recording capacity becomesnecessary. For example, in the case where recording of image data usingthe normal picture recording and that using the alarm picture recordingare executed at the same time, however, the normal recording is executedat a low frame rate (for example, 1 fps) in many cases. As compared withthe problem posed in the scheme described with reference to FIGS. 12 and13, therefore, a serious problem is not posed.

As for the alarm picture recording, it is necessary to go back in timeseries and record the video image (pre-alarm image) preceding the alarmoccurrence time. Therefore, it is difficult to make image data obtainedby the normal picture recording and image data obtained by the alarmpicture recording coexist in the same channel. In a configuration inwhich a video image of one web camera is stored in one channel in a timeseries manner and the video image of one web camera is divided into andstored in two channels such as the normal channel and the alarm channel,the configuration of the recording system can be simplified. By the way,it is also possible to use a configuration in which the video image ofone web camera is divided into and stored in three or more channels.

Furthermore, according to the image reproduction method (seamlessreproduction) of the present invention, it is possible to, for example,reproduce recorded video images of two kinds generated from one cameraon one reproduction screen as if they are one video stream for the user.

The configuration for the image reproduction method according to thepresent invention is not restricted to the configurations heretoforedescribed, but various configurations may be used.

By the way, it is also possible to provide the present invention as, forexample, a method or a scheme for executing the processing according tothe present invention, or a program for implementing such a method or ascheme. It is also possible to provide the present invention as variousapparatuses, such as an image reproduction apparatus, or systems.

Application fields of the present invention are not restricted to thosedescribed heretofore, but the present invention can be applied tovarious fields. For example, the embodiment has been described by takingthe video image generated by the camera in the surveillance system as anexample, but the application field of the present invention is notlimited to this. For example, it is also possible to handle a videoimage concerning a movie or a TV program.

As for various kinds of processing conducted in the image reproductionmethod according to the present invention, for example, a configurationcontrolled by causing a processor to execute a control program stored ina ROM (Read Only Memory) in hardware resources including the processorand the memory may be used. A configuration of a hardware circuit inwhich, for example, respective function means for executing theprocessing are independent may also be used.

Furthermore, it is also possible to grasp the present invention as acomputer-readable recording medium, such as a floppy (trade mark) diskor a CD (Compact Disc)-ROM, storing the control program and a controlprogram (itself). It is possible to perform the processing according tothe present invention by inputting the control program from therecording medium to the computer and causing the processor to executethe control program.

The embodiment has been described. However, the present invention is notlimited to the embodiment. It is evident to those skilled in the artthat various changes and modification can be effected without departingfrom the spirit of the present invention and appended claims.

INDUSTRIAL APPLICABILITY

The present invention can be utilized as, for example, a method or ascheme for executing processing according to the present invention, or aprogram for implementing such a method or scheme. Furthermore, it isalso possible to utilize the present invention as various apparatuses,such as the image reproduction apparatus, and various systems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a general configuration of an image storageand delivery system according to an embodiment of the present invention;

FIG. 2 is a diagram showing recording contents of a disk deviceaccording to an embodiment of the present invention;

FIG. 3 is a diagram showing operation of recording into a disk deviceaccording to an embodiment of the present invention;

FIG. 4 is a diagram showing image reproduction processing according toan embodiment of the present invention;

FIG. 5 is a diagram showing image reproduction processing according toan embodiment of the present invention;

FIG. 6 is a diagram showing image reproduction processing according toan embodiment of the present invention;

FIG. 7 is a flow chart showing image reproduction processing accordingto an embodiment of the present invention;

FIG. 8 is a diagram showing a configuration of a memory area accordingto an embodiment of the present invention;

FIG. 9 is a flow chart showing image reproduction processing accordingto an embodiment of the present invention;

FIG. 10A is a diagram showing an example of recording contents andreproduction contents according to an embodiment of the presentinvention;

FIG. 10B is a diagram showing an example of recording contents andreproduction contents according to an embodiment of the presentinvention;

FIG. 10C is a diagram showing an example of recording contents andreproduction contents according to an embodiment of the presentinvention;

FIG. 11A is a diagram showing an example of recording contents andreproduction contents according to an embodiment of the presentinvention;

FIG. 11B is a diagram showing an example of recording contents andreproduction contents according to an embodiment of the presentinvention;

FIG. 11C is a diagram showing an example of recording contents andreproduction contents according to an embodiment of the presentinvention;

FIG. 11D is a diagram showing an example of recording contents andreproduction contents according to an embodiment of the presentinvention;

FIG. 12 is a diagram showing an example of processing in the case whererecording using different recording modes is conducted in one channelaccording to an embodiment of the present invention;

FIG. 13 is a diagram showing an example of processing in the case whererecording using different recording modes is conducted in one channelaccording to an embodiment of the present invention; and

FIG. 14 is a diagram showing an example of a table for managingrecording contents according to an embodiment of the present invention.

DESCRIPTION OF REFERENCE NUMERALS

-   -   1: Image storage and deliver server    -   3: Disk device    -   4: Network    -   5: Web camera    -   6: Client terminal    -   30: Storage area

1. An image display method for recording a moving picture formed of aplurality of still pictures obtained from one image pickup device into arecording device using a plurality of channel lines having differentpicture qualities in a duplicative manner, and displaying the movingpicture recorded in the recording device, comprising: image acquisitionstep of acquiring the still pictures forming the moving picture from therecording device; and image display step of displaying acquired stillpictures, wherein the still pictures forming the moving picture in achannel line having a high picture quality among the channel lines aredisplayed preferentially.
 2. The image display method according to claim1, wherein the still pictures have time information, and at said imageacquisition step, the still pictures forming the moving picture acquiredfrom the recording device are selected on the basis of the timeinformation and reproduction reference time.
 3. The image display methodaccording to claim 1, wherein at said image display step, the stillpictures forming the moving picture in the channel line having the highpicture quality are displayed while the still pictures forming themoving picture in the channel line having the high picture quality areconsecutively present.
 4. The image display method according to claim 1,wherein the picture quality indicates at least one of a frame rate, acompression factor, and a resolution, and the high picture qualityindicates at least one of a high frame rate, a low compression factor,and a high resolution.
 5. An image display apparatus for recording amoving picture formed of a plurality of still pictures obtained from oneimage pickup device into a recording device using a plurality of channellines having different picture qualities in a duplicative manner, anddisplaying the moving picture recorded in the recording device,comprising: image acquisition means for acquiring still pictures formingthe moving picture from the recording device; and image display meansfor displaying acquired still pictures, wherein the still picturesforming the moving picture in a channel line having a high picturequality among the channel lines are displayed preferentially.
 6. Theimage display apparatus according to claim 5, wherein the still pictureshave time information, and said image acquisition means selects thestill pictures forming the moving picture acquired from the recordingdevice on the basis of the time information and reproduction referencetime.
 7. The image display apparatus according to claim 5, wherein saidimage display means displays the still pictures forming the movingpicture in the channel line having the high picture quality while thestill pictures forming the moving picture of the system having the highpicture quality are consecutively present.
 8. The image displayapparatus according to claim 5, wherein the picture quality indicates atleast one of a frame rate, a compression factor, and a resolution, andthe high picture quality indicates at least one of a high frame rate, alow compression factor, and a high resolution.
 9. A program for causinga computer included in an image display apparatus to execute a functionof the image display apparatus for recording a moving picture formed ofa plurality of still pictures obtained from one image pickup device intoa recording device using a plurality of channel lines having differentpicture qualities in a duplicative manner, and displaying the movingpicture recorded in the recording device, comprising: an imageacquisition function of acquiring the still pictures forming the movingpicture from the recording device; and an image display function ofdisplaying acquired still pictures, wherein displaying the stillpictures forming the moving picture in a channel line having a highpicture quality among the channel lines preferentially is implemented bythe computer.
 10. The program according to claim 9, wherein the stillpictures have time information, and said image acquisition functioncomprises selecting the still pictures forming the moving pictureacquired from the recording device on the basis of the time informationand reproduction reference time.
 11. A program according to claim 9,wherein said image display function comprises displaying the stillpictures forming the moving picture in the channel line having the highpicture quality while the still pictures forming the moving picture ofthe channel line having the high picture quality are consecutivelypresent.
 12. The program according to claim 9, wherein the picturequality indicates at least one of a frame rate, a compression factor,and a resolution, and the high picture quality indicates at least one ofa high frame rate, a low compression factor, and a high resolution.